Occupants' influence on air change in dwellings.

The occupants' behaviour is one of the parameters which has the greatest influence on the air change in the dwelling. This applies both to naturally and to mechanically ventilated dwellings. On the basis of continuous measurement of the air change in 25 dwellings, the relation between the ventilation system and air change and between the number of occupants and air change is discussed. The air change in the 25 dwellings has been measured for a period of about one week during occupancy. The measuring principle applied is "the method with constant concentration of tracer gas". Even though the average air change for occupied dwellings is higher than the rate normally recommended in Denmark, some 20% of the dwellings have, nevertheless, an extremely low rate of air change. Only a small percentage of the dwellings have ventilation systems that can be adjusted to provide the desired rate of air change. The mechanical ventilation system usually gives too high a rate of air change, while the natural ventilation system usually provides too low a rate. Improved control of the total air change would achieve both energy savings and a better indoor climate.